1. Field of the Invention
This invention relates to a semiconductor device having a microprocessor (hereinafter called "MPU"), and particularly to a method of identifying specifications of a peripheral device such as a non-volatile memory or the like used by being electrically connected to an input/output port (hereinafter called "I/O port") of the semiconductor device.
2. Description of the Related Art
In addition to a read-only memory (hereinafter called "ROM") for storing control programs therein and a random-access memory (hereinafter called "RAM") for writing processing data therein and reading it therefrom, a peripheral device is installed in a semiconductor device equipped with a recent MPU so that the extension or the like of its processing operation can be performed in cooperation with the MPU. The peripheral device is electrically connected to the MPU or the like through an I/O port of the semiconductor device. Various specifications are provided for the peripheral device. Even in the case of a non-volatile memory corresponding to one peripheral device, for example, there are known two types: one which is used as a two-wire type wherein a peripheral device is electrically connected to an MPU at two connecting terminals and another which is used as a five-wire type wherein a peripheral device is electrically connected to an MPU at five connecting terminals. Thus, since the peripheral devices installed in semiconductor devices are different from each other in specifications (the number of connecting terminals), it is necessary to prepare or provide control programs corresponding to their peripheral devices. Further, since there is one which is not equipped with the peripheral device, it is necessary to prepare control programs for its sake.
Such control programs are to be stored in the ROM incorporated in the semiconductor device together with the MPU or a memory incorporated in the MPU.
In such a case, however, the semiconductor device must include individually prepared ROMs storing therein the control programs corresponding to the presence or absence of provision of each peripheral device or the specifications of the peripheral devices. Thus, the fabrication of the semiconductor device becomes complex.
Particularly when the control programs are set in the memory incorporated in the MPU, photomasks for manufacturing the MPU must be prepared for every type of control program stored in the built-in memory. Thus, the MPU not only increases in fabrication complexity, but also increases in manufacturing cost.
It is also hard to mass-produce the semiconductor device due to the fact that its fabrication becomes complex.
With the foregoing problems in view, it is an object of the present invention to provide a semiconductor device capable of overcoming the requirement for complexity in process of its fabrication, an increase in its cost, and difficulties in its mass production and carrying out its manufacture in common with others regardless of specifications of a peripheral device.
It is another object of the present invention to realize the above object without adding a special configuration to the semiconductor device.